Method of beveling the ends of inner tubes



Nov. 15, 1927. 1,649,358

c. EIMAYNARD METHOD OF BEVELQNG THE ENDS 0F INNER TUBES Filed Dec. 31926 I N V EN TOR.

A'TI NEY.

Patented Nov. 15, 1927.

PATET CHARLES EDGAR MAYNARD, OF NORTHAMPTON, MASSACHUSETTS, ASSIGNGR TFISK RUBBER COMPANY, OF CHICOPEE FALLS, MASSACHUSETTS, A GOEPOIELATIGNOF MASSACHUSETTS.

fln'rnon or BEVELING THE suns or runes TUBES.

Application filed December so, was. Serial no. wanes.

This invention relates to the manufacture of inner'tubes for automobiletires. It has particular reference to the production of a gradual,pointed, and accurate skive or taper '5 upon the end of the tube withoutWaste of material and'by a method adaptable to the requirements ofquantity production.

The invention will be described in connection with the accompanyingdrawings, in 10 Which- Fig. 1 is a detail of the end of a tube mountedupon a mandrel;

Fig. 2 is a similar view showing the trim ming of the tube to length;

F 1g. .3 is a similar view showing the an plication of a single ply endportion on the material;

Fig. 4c is a similar view showing one manner of bindin the tube end tothe mandrel for 'vulcanization;

gig. 5 is a detail of the vulcanized tube en 4 Figs. 6, 7, 8 and 9 areviews corresponding: to Figs. 1, 2, 4: and 5 respectively but illnstrating one method formerly practiced and. the resulting tube end; and

Fig. 10 is a detail of a special form ofsheetstock used in one prior artmethod.

In the manufacture of'inner tubes it is necessary to=sl ive or bevel theends of the tube before it is s liced into annular form.

i, however, be considerably less (say 1 inches) than in the processdescribed in sonin order to avoid a rupt transitions in wall thicknessTubes intended Orwell-base or drop-center balloon rims need very carefulskiving in order to give the tube uniform expansibility. Generally thisskiving has been done upon a special.- machine operating to trim andbevel the vulcanized tube after re moval from t e mandrel. cess, hasalso can had in the skiving of the tube while. on the mandrel and:during the vulcanizing process, appliances for this purpose having akent e .form' of metallic clamps or cufl's, rubber bands, or a wrapping offabric.

An example of the last-mentioned method is shown in Figs. 6 to 9. Thetube 10, mounted on a mandrel 11, is cutat-12 to a definite length, across cut 13 enabling the waste end 14 to be removed for reworking. Ahelical wrapping 15 of fabric ta e is now placed tightly aroundthetubeen binding the latter against themandrel and causing a flow stockindicated in Fig. 10. lhe ends of this able to either the sheet ortheextra 10'.

Considerable sue "acter of skive appears. -tr1mmed accurately to lengthon of the rubber. After removei per, which generally is-left on duicanization in order to seal the end of against ingress of thevulcanizing iluld as well as to mold the rubber into the desiredv skive,the tube end has the appearance in Fig. 9. The skive thus produced is asat 16, and gives neither gradual trait of thickness nor the even moredesirable n iform expansibility. Attempts have been made to improve thisskive by using a special sheet stock were stepped otfas a 17 thereby poducing a ,tube end having a single instead of a double thickness whenthe stools, as is custernary, is rolled twice around the Much diiticultyis experienced, however, in J" the practice of this method, since it ish. to place the sheet with absolute accurac c the mandrel, and since thenature of the c on the end of the sheet is not adapted for production bymachinery at. high spec r Moreover, the method is not adaptable tubesproduced by the extrusion moth i.

i have devised a method which is uh method of producing tubes, and whichavoids the objections to the methods outlined above. According tom}?method the rubber tube 20, mounted on the mandrel 21, is. severed tolength at The length of the tube may,

nection with Figs.- ti to 9. The Waste end is removed as before, butbefore wrapping down theend of the tube a strip of rubber 25. of lessthan the thickness of the tube {r Y .venic-ntly about half of it) isWound are the tube end as in Fig. 3, ."5' ends either butt or lapjointed. ping 9.6 has been applied canized, the end 27 takes on theappeai of Fig? 5, in which the much improved at The tube being? themandrel preserves this accuracy afte ul'cauization, and presents an endportion of improved. iiformity, sharpness, and smoothness of as comparedwith any prior process.

Having thus described my invention, Ti claim:

1. A method of producing a slrived end on a rubber tube which comprisesmounting trimming the and Uni-ed length, apa, s'vi}; 01% In?) es, oflessgauge than @112 had of the tube, to the tube end so 5.1m; it EL." 3- 1111: 1 ihs tube and. pmtly upon the )ressing the and 0f the tube 112 1431,and vuicanizing the cf 'nreducin & skiwd end.

on rubber tube which comprisas mounting the tube upon a mandrel,applying a strip of rubber, of less gauge than the body of the tube, isthe tube em 50 'hat it is joined to she tube and lies partly upon themanch'el, compressing the end 0f the tube against the mandrel andvulcanizing the tube.

CHARLES EDGAR MAYNARD.

